How to convert Java.Util.Date to System.DateTime

Question

In Xamarin.Android, you work with both .NET and Java.

I get a return value of Java.Util.Date, I then need to input that same value as a parameter that only takes System.DateTime

This is how I currently do it

public static DateTime ConvertJavaDateToDateTime(Date date)
{
    var a = date.ToGMTString();
    var b = date.ToLocaleString();
    var c = date.ToString();
    DateTime datetime = DateTime.ParseExact(date.ToGMTString(), "dd MMM yyyy HH:mm:ss 'GMT'", CultureInfo.InvariantCulture);
    return datetime;
}

However on the first 9 days of any month, I only get 1 digit for the day, and the DateTime.ParseExact function is looking for dd (i.e. 2 digits for the day).

a is a string with value "1 Sep 2014 14:32:25 GMT"

b is a string with value "1 Sep 2014 16:32:25"

c is a string with value "Mon Sep 01 16:32:25 EET 2014"

I wish I could find a simple, quick, reliable and consistent solution for this problem :D

Answer 1

java.util.Date has a getTime() method, which returns the date as a millisecond value. The value is the number of milliseconds since Jan. 1, 1970, midnight GMT.

With that knowledge, you can construct a System.DateTime, that matches this value like so:

public DateTime FromUnixTime(long unixTimeMillis)
{
    var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
    return epoch.AddMilliseconds(unixTimeMillis);
}

(method taken from this answer)